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Replacing internal filter...

Discussion in 'Fisher Engineering Discussion' started by mkwl, Nov 10, 2008.

  1. mkwl

    mkwl 2000 Club Member
    Messages: 2,362

    Can someone please outline how to change the filter for the fluid on my MMII insta-act plow? There's nothing about how to do this in my manual- only how to change the fluid- how often should the filter really be changed?
  2. 04f250fisher

    04f250fisher Senior Member
    Messages: 105

    Unscrew the drain plug on the resevor, drain out the fluid then unscrew the 4 screws on the reservoir. You may need to unbolt the whole pump to drop the reservoir belive there are two 9/16 bolts but use a rubber mallet and "tap" the canister off the O-ring. Make sure you clean out the bottem of the canister as well as the magnet at the bottem. The filter is small and tube shaped. Pull it off, might be kinda hard but it will budge. Press the new one on and reassemble and i think its 1 and a half quarts of fisher fluid, there is a side plug can unscrew that marks the level. I change mine every fall.
  3. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    To do a good drain and refill you want to remove the hoses from both the lift cylinder and angle cylinders as well as drain the reservoir to insure your getting as much old fluid out as possible.

    If the plow is a few seasons old go ahead and remove the reservoir and wipe the inside out, clean the magnet while your in there, and either clean or replace the pickup filter screen. If it's an older Flostat pump- make sure it has the updated pickup/retainer on it. If it doesn't, head over to the dealer and pick one up.

    If you want to do an actual flush then you'll either need to purchase extra fluid of whatever type your using to use as a flush, or use Meyer's genuine Hydra-Flush fluid to clean a neglected or very dirty system.

    After its completely drained and re-assembled, refill the reservoir with either your flushing fluid or your normal plow oil if your doing a flush.

    Now, the part that usually causes guys so much grief is that they do not take the time to get the air out of the system...or they rush the re fill procedure...usually the latter.

    After filling to the correct level, fully lift the plow up ONCE....and then angle it fully left and right ONCE. Lower the plow back to the ground, push the lift cyl the rest of the way down...

    Now crack the fill cap open (be ready for possible pressure build up) and remove the plug in order to check the fluid level and add as necessary, but also look to see if the fluid is aerated. If it is, let the plow set for a while to allow any air trapped in the fluid to settle out. You can not rush this procedure or you'll only make extra work/mess and/or frustration for yourself. You have to be careful not to over operate the plow while refilling initially because once you aerate the fluid...your done for at least a couple hours until the air settles out of the fluid and no amount of cycling will purge the air...in fact it'll only make it worse.

    With the fluid clear operate the plow again once or twice then set it on the ground and push the cylinder down again and re check the fluid. Do this procedure until the fluid level remains consistent and is free of any air bubbles.

    If your doing a flush first, it isn't necessary to be concerned with air in the system since you'll simply be draining it after a brief operation anyway. Follow the refill procedure after you do the flush and your ready to do the final fill.

    I like to recheck the fluid level one last time after the first full use if I have the oppertunity.
  4. mkwl

    mkwl 2000 Club Member
    Messages: 2,362

    Okay- my only concern is- the screws holding it on are pretty well rusted- I don't really want to have them shear off into the valve block- should I be worried about them shearing? If they won't come loose will I be okay with just a fluid change?

  5. bribrius

    bribrius PlowSite.com Addict
    Messages: 1,609

    mine were rusty but didnt shear off.

    try wd 40? i dunno.

    can try to just change fluid and not filter. But if filter is clogged it still wont work. Or if the retainer clip isnt on holding the tube in place the tube could fall and the plow could not work. Or if you dont clean the bottom of the reservoir (all kinds of gunk probably) it will just dirty the fluid your putting in and at some point the reservoir will be so full of grime it will clog the filter and plow wont work. Same with magnet. magnet keeps the metal particles from being sucked in which will clog the filter and PLOW WONT WORK.

    So yeah. you can avoid it and the plow might still work. But avoidance isnt a solution because at some point PLOW WONT WORK.

    filter how often?? heavy use . maybe every year or two? normal use.... four or five +. I actually know someone that hasnt ever changed his and i think its seven years old now.

    Last edited: Nov 11, 2008
  6. mkwl

    mkwl 2000 Club Member
    Messages: 2,362

    In what year did Fisher start making the MMII?
  7. bribrius

    bribrius PlowSite.com Addict
    Messages: 1,609

    2000 .....
  8. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    The reservoir screws can and do break off in the valve body. If they look real bad spray them with some penetrating fluid for at least a few days before attempting removal. You can use a little heat on them but you have to be careful with it. Have had good success with a pencil torch.

    If you do break any off then it's time to pull the pump unit off the headgear and get the drill or welder out.

    For preventative purposes I like to replace them with stainless screws with a good dose of anti-seize at removal time. Helps to insure easy removal the next time.
  9. PLM-1

    PLM-1 Senior Member
    Messages: 424

    Where is a good place to buy a new filter and fluid online? I don't have any dealers close by.
  10. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    • Central Parts Warehouse
    • Angelos
    • Mill Supply
  11. mkwl

    mkwl 2000 Club Member
    Messages: 2,362

    Okay- did the procedure over the weekend- got it all put back together, everything seems to be in order. There was like 1/4" of black "slime" at the bottom of the resivoir- what is this? Cleaned it all up- glad I did- wouldn't want to have all that junk in the resivoir.
  12. mikelawtown

    mikelawtown Senior Member
    from Mass
    Messages: 429

    delete please
    Last edited: Nov 17, 2008
  13. mikelawtown

    mikelawtown Senior Member
    from Mass
    Messages: 429

    I have a bud that lives in dracut mass and has a couple trucks he wants flushed and filled but doesnt get out till dark, where can he get it done and what the going rate?Thanks
  14. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    It's from lack of maintenance Matt. :D

    Which is why it's so important to do. The black crud is mostly from the packings in the lift ram and angle cylinders wearing. As they wear from use they shed small bits and fine pieces into the fluid, and ultimately end up collecting in the reservoir. If left for too long can and will plug the pickup screen and other components in the hydro system. Sounds like you got it in time. :waving:
  15. Flipper

    Flipper PlowSite.com Addict
    from CT
    Messages: 1,180

    I always replace both the resevoir screws as well as the screws for the plastic covers for the solenoid valves with stainless allen head screws. Makes removal the next time much easier.
  16. mkwl

    mkwl 2000 Club Member
    Messages: 2,362

    I see- jeez- plow isn't even that old either (I'm guessing around a 2004).

    Yeah, I can see how that would happen- I think I'm good though for htis season- it really wasn't that bad to take the resivoir off etc to clean the intake filter and clean the resivoir- I'll probably do it every year from here on in.

    Yeah, I'm glad I took the time to clean it out!
  17. wildbl1500

    wildbl1500 Senior Member
    Messages: 111

    I know this is an old thread, but does anyone know how many quarts of fluid are needed for the system? Also, any idea of part number for the filter?
  18. plowguy43

    plowguy43 PlowSite Fanatic
    Messages: 5,281

    Filter - 26781
    I'm pretty sure it'll only take 1 1/2 quarts. I filled mine last week and it was all it would take.
  19. wildbl1500

    wildbl1500 Senior Member
    Messages: 111

    Thanks Bob.
  20. BlizzardBeater

    BlizzardBeater Senior Member
    from Maine
    Messages: 420

    Wow, good time to pull up an old thread. I gotta do my plows this weekend. Anybody remember what size the bolts that hold the resevoir on are, length and thread? I'd like to make sure I got some out in the shop before I start pulling them apart. They've been in and out enough times that they should be changed :)